"If the whole planet were to suddenly switch to organic farming tomorrow, it would be an ecological disaster," he said.

In terms of yields, he continued, organic food is the "productive equivalent of driving an S.U.V."

Mr. Mack also addressed what he called the "mistaken belief that natural is always better."

Pesticides that help crops to grow more efficiently in this country, he argued, "have been proven safe and effective and absolutely not harmful to the environment or to humans," and have been certified as such by the Food and Drug Administration or the Environmental Protection Agency.

The implication of not believing that pesticides are safe, he said, is that you don't trust the government's findings.

"Once you go down that path, I don't know where the guard rails are," he said.

Mr. Mack dismissed the notion that Syngenta, a company that sold nearly $12 billion of seeds and "crop protection" technologies last year, felt threatened by the organic movement.

His concern, he said, was to make people aware of the limitations of organic food.